By default v.out.postgis exports vector data as simple
features, ie. boundaries and centroids (forming topological
areas) become polygons, isles become holes. Geometry of simple feature
elements is stored in PostGIS feature table in the column named
"geom". Name of the geometry column can be changed
by options=GEOMETRY_NAME=<column>. Note that for
exporting vector features as simple features can be alternatively
used PostgreSQL driver
from OGR library
through v.out.ogr module.

Also note that it's allowed to store in the feature table only
features of the same type, ie. mixing of points and lines is not
currently possible. The feature type is determined for output feature
table from the first vector feature accessing data sequentially
(type=auto). Vector features of other types are during export
skipped. User can choose preferable feature type by type
parameter. Only single type is currently allowed (see TODO section for
details).

v.out.postgis currently supports only three basic output
simple feature types: Points, Linestrings and Polygons. Also 3D
features of the same type are supported, eg. 3D points are exported
as PointZ simple feature. Faces are exported as 3D
polygons. 3D features are written to the output automatically if input
vector map is 3D. If -2 flag is given then the output is always
2D (z-coordinate is silently ignored for 3D input vector maps).

Multigeometries are not currently supported. Features with the same
category are exported as multiple singe features.

Tables node, edge and face are stored in given
topological schema. By default v.out.postgis defines its name
as topo_<input>. Alternatively, the name for topology
schema can be defined
by options=TOPOSCHEMA_NAME=<name>.

In this case GRASS vector data are exported to PostGIS database using
OGR library, namely using PostgreSQL driver. Contrary to
the v.out.ogr
module, v.out.postgis is using directly PostGIS data provider
which is part of GRASS vector engine. Beside
that, v.out.postgis is optimized for PostGIS export including
topological access to the data.

Example below demonstrates how to define name for geometry column and
disable building spatial index. Spatial reference system is defined
by srid identifier which corresponds in this case with EPSG
3358 (North Carolina dataset).

Exported data can be linked as vector map created in the current
mapset by specifying output_link parameter. In the example below
vector map "busstopsall" from PERMANENT mapset is exported
into "grass" PostGIS database. v.out.postgis after
successful export also creates in the current mapset GRASS vector map
as a link to the PostGIS feature table.

v.out.postgis allows ignoring attributes when exporting
vector features by specifying -t flag.
Command below exports vector features without attributes. The feature
will contain only two columns, the fid and geometry column.